1. Field
The present invention relates generally to magnetic storage tape read and/or write heads, and more particularly to multi-format magnetic storage tape read and/or write heads.
2. Description of the Related Art
Magnetic storage tape continues to be an efficient and effective medium for data storage in computer systems. Increased data storage capacity and retrieval performance is desired of all commercially viable mass storage devices and media. In the case of linear tape recording, a popular trend is toward multi-head, multi-channel fixed head structures with narrowed recording gaps and data track widths so that many linear data tracks may be achieved on a tape medium of a predetermined width, such as one-half inch width tape. To increase the storage density and reduce access time of magnetic tapes, data tracks on the tape are arranged with greater density and the tape is streamed by a tape head at increasingly faster rates.
Magnetic tape heads typically include an active device region including raised strips or ridges, commonly referred to as islands, bumps, or rails, that provide a raised tape support or wear surface across which the magnetic tape advances. One or more of these raised islands includes embedded data transducers. The embedded transducers can be either a recording element for writing information to a magnetic tape or a reproducing element for reading information from a magnetic tape. An embedded recording element produces a magnetic field in the vicinity of a small gap in the core of the element, which causes information to be stored on a magnetic tape as the tape advances across the support surface. In contrast, a reproducing element detects a magnetic field from the surface of a magnetic tape as the tape advances over the support surface. Additionally, raised islands may be included without transducers to help support and guide the magnetic tape over the head, generally referred to as outriggers.
Typically, a plurality of embedded transducers are spaced transversely across a direction of tape transport. The transducers may be sized and disposed along an island for varying storage tape data formats, e.g., different numbers of channels, track widths, and track densities. For example, a four channel head includes four read and four write transducers spaced transversely across a tape path. The width of the read/write transducers and the distance between adjacent read/write transducers is associated with the density of tracks to be written to and read from the storage tape. Storage capacity of magnetic tapes are generally increased with the use of smaller more closely positioned read/write transducers in the tape head. Thus, as storage capacities increase, the tape head configuration and stored data formats are changed.
As the storage tape and tape drive industry evolves and achieves increases in storage capacity, the tape head and media designs continue to make changes from one generation to the next. For instance, new data formats with more densely positioned read/write transducer elements on tape heads, more densely positioned tracks on the storage tape, and thinner storage tape increases the storage capacity of storage tape devices. Format changes in the tape head and storage tape, however, generally make it difficult to read and/or write to earlier generation storage media without compromising the desired storage capacity target. For example, to increase storage capacity of storage tape, the storage tape may be thinned, e.g., lower magnetization thickness (Mrt), while narrowing and thinning the magneto resistive (MR) elements in the head. Narrowing and thinning the MR elements in the head may present reliability and durability problems when the optimized thin tape head back-reads to prior generation thick media. Therefore, to provide compatibility with multiple format storage tapes, e.g., prior generation formats, a compromise is typically made where the tape head design and storage tape format are marginalized and therefore not optimized for reliability and increased storage capacity.
In addition to marginalizing the head to preserve the ability to read earlier generation or varying formats, utilizing a completely separate back-read head may provide a system to read (or write) earlier or varying data formats. A separate back-read head, however, takes up precious space in the drive with its own set of complicated mechanics and electronics. Additionally, a separate back-read head adds cost and complexity to the media drive system.